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### Topic: Current question (Read 3279 times)previous topic - next topic

#### skyjumper

##### Mar 24, 2011, 11:55 am
Hi All...

So, if I have a chip that uses .65 micro amp (.65 uA) and another that uses 100 nA, which is using less power? I don't know what an "nA" is...

Thanks...

#1
100 nA = .1 uA

#### skyjumper

#2
##### Mar 24, 2011, 12:46 pm
Oh, a HUGE difference then, thank you!

#### pascelui

#3
##### Mar 25, 2011, 08:57 am
If you're interested it would be a good idea to read up on SI prefixes:

http://en.wikipedia.org/wiki/Si_prefix.

Specifically you said you don't know what "nA" stands for; it means nanoampere(s).

One "nano-amp" is one billionth of an ampere, or, as retrolefty said, one thousandth of a "micro-amp".

#### MarkT

#4
##### Mar 25, 2011, 05:35 pm
The commonly used prefixes differ by a factor of a thousand...

1G = 1,000,000,000 (giga) - rarely seen in electronics
1M = 1,000,000 (mega)
1k  = 1,000 (kilo)

1m = 0.001 (milli)
1u  = 0.000001 (micro - the correct symbol is a greek letter mu but my keyboard doesn't have that!)
1n = 0.000000001 (nano)
1p = 0.000000000001 (pico)

For historical reasons (which annoy me) capacitance values that naturally fall in the nano range are often given in micro or pico range:

47,000pF (more naturally expressed as 47nF)
0.001uF (much more sensible to say 1nF)

This reluctance for the electronics industry to use nano prefix is probably why you aren't confident about it.  Oddly the same thing does not happen with inductance values where nH are routinely used.

[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### AWOL

#5
##### Mar 25, 2011, 05:56 pmLast Edit: Mar 25, 2011, 05:58 pm by AWOL Reason: 1
Quote
1G = 1 000 000 000 (giga) - rarely seen in electronics

Unless you work with RF.
Or processor clocks.
Or (in my case) both.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#### bill2009

#6
##### Mar 25, 2011, 06:24 pm
Quote

For historical reasons (which annoy me) capacitance values that naturally fall in the nano range are often given in micro or pico range:

47,000pF (more naturally expressed as 47nF)
0.001uF (much more sensible to say 1nF)

This reluctance for the electronics industry to use nano prefix is probably why you aren't confident about it.  Oddly the same thing does not happen with inductance values where nH are routinely used.

+1 on the annoyance.  it also leads to confusion about pf because the uninitiated may think "oh, well - they must meant .001uf"

#### cmiyc

#7
##### Mar 26, 2011, 08:33 pm

if I have a chip that uses .65 micro amp (.65 uA) and another that uses 100 nA, which is using less power?

Are they at the same voltage?  Power is determined by Voltage and Current, not just one alone.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

#### Grumpy_Mike

#8
##### Mar 28, 2011, 11:45 pm
nF is a new fanged way of indicating a value. Twenty years ago no one used it, mainly because it was an odd power. That is the jump from Farads to micro Farads, ( ten to the minus six) is the same size as the jump to pico farads (ten to the minus 12). It was not used in inductors mainly because values in the nH were not used as electronics didn't go up to those sorts of frequencies.
But as you say history annoys you, why were we all so stupid in those days? It must be great being clever.

(If you are from the U.S. then please look up the meaning of irony)

#### retrolefty

#9
##### Mar 29, 2011, 03:29 am
Quote
(If you are from the U.S. then please look up the meaning of irony)

Sorry no time, I'm busy trying to program an arduino to change my auto speedometer to read out in furlongs per fortnight.

Lefty

#### westfw

#10
##### Mar 29, 2011, 08:20 am
Huh.  How recent *is* the whole "engineering notation" that uses multiples of three for the exponent in scientific notation?  I mean, when I learned about the metric system, we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used.  But the bigger prefixs (nano, giga, terra, peta, etc) were rarely used then, perhaps because it wasn't common for measured things to be that big or small (with perhaps the single exception of picoFarads, which were sometimes micro-micro-Farads, but those were only for electronics/physics geeks.)

#### AWOL

#11
##### Mar 29, 2011, 10:41 am
Quote
we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used.

And then, of course, there's the entomologists.
"Millipedes"?
"Centipedes"?
Utter tosh.
They are, surely, kilopedes and hectopedes respectively.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#### kg4wsv

#12
##### Mar 29, 2011, 03:47 pm
Quote
I mean, when I learned about the metric system, we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used.

They still are.  I keep seeing those on my daughter's homework, and I want to scream (mostly because I don't remember them).

There is that centi-meter thingy, though.

Quote
(If you are from the U.S. then please look up the meaning of irony)

containing iron?

-j

#### AWOL

#13
##### Mar 29, 2011, 03:55 pm
I think things like "hect-" only really come into use for square measure, like "hectare", which is an area of 10 000 square metres.
The are is (the are are?) 100 square metres, or ten metres by ten metres.
Using third powers of ten would make for peculiar measurements, i.e., a kiloare would be 100 000 metres square, and would be 316.227 metres on a side.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#### MarkT

#14
##### Mar 29, 2011, 06:49 pm
There's decibels of course and decilitres are sometimes used, but otherwise only centi has survived (centimetre, centilitre) in the real world. Hectare is the unit to all intents and purposes, no-one uses ares do they?  Angstroms are gradually losing the battle to nanometres.

And then there's all the informal units http://en.wikipedia.org/wiki/List_of_unusual_units_of_measurement
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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